Two-stage reconstituting injector

ABSTRACT

An injector ( 10 ) for injecting a medicament into a patient. The injector includes a container ( 18 ) defining a first chamber ( 22 ), which contains a fluid therein, and a second chamber ( 23 ). The injector also includes an injection conduit ( 126 ) configured for directing the fluid fired from the container into the patient. A transfer mechanism is operable by a user to transfer the fluid from the first chamber to the second chamber in a first stage of operation, and a firing mechanism is operable by the user for firing the fluid from the second chamber through the injection conduit in a second stage of operation. An energy source ( 62 ) is in powering association with the firing mechanism to drive firing mechanism in the first and second stages.

FIELD OF THE INVENTION

The present invention relates to an injector, and more particularly toan injector in which materials from at least two compartments arecontained before the injection is made.

BACKGROUND OF THE PRESENT INVENTION

Known injection devices for injection of medicaments into a patientinclude traditional hypodermic needle syringes, needle-free jetinjectors like the ones disclosed in U.S. Pat. Nos. 5,599,302;5,062,830; and 4,790,824; needle-assisted injectors, such as thosedescribed in U.S. Patent Publication No. 2005/0033234; andself-injectors or autoinjectors like the ones disclosed in U.S. Pat.Nos. 4,553,962 and 4,378,015, and PCT Publications WO 95/29720 and WO97/14455.

The liquid medicament preparations that are injected from such injectiondevices are also known to contain insoluble or particulate drugconstituents. This can be due to the insolubility of the drug in thevehicle or medium in which it is stored. As a result, the insoluble orparticulate drug constituents in the liquid preparations separate uponstorage, even over short periods of time.

The particulates can potentially clog the needle, and this isparticularly problematic in cases when the liquid pharmaceuticalpreparation containing insoluble particles is self-administered oradministered in the home by non-professional care-givers. Ordinarily,when these liquid pharmaceutical preparations are administered in thehospital or other health-care providing institutions by trained staff,one can rely on adequate handling of the medication to ensure properdrug delivery, despite settled material and plugged needles. Howeverwhen such pharmaceutical preparations are self-administered oradministered in the home by non-professional care-givers, the risk forinadequate handling of the medication increases since the injection ofsuch formulations requires that the administrator be able to adequatelyresuspend any settled material and clear the needle to ensure properdrug delivery.

Thus, an injector is needed that can facilitate reliable combination ofinjectable components prior to injection.

SUMMARY OF THE INVENTION

The invention is related to an injector for injecting a medicament intoa patient. The preferred embodiment of the injector includes a containerdefining a first chamber containing a fluid therein, and a secondchamber. An injection conduit is configured for directing the fluidfired from the container into the patient. The injector also includes atransfer mechanism operable by a user to transfer the fluid from thefirst chamber to the second chamber in a first stage of operation, and afiring mechanism operable by the user for firing the fluid from thesecond chamber through the injection conduit in a second stage ofoperation. An energy source is in powering association with the firingmechanism to drive firing mechanism in the first and second stages.

Preferably, the injector also includes a transfer control that ismanually operable to operate the injector in the first stage ofoperation. The first stage preferably also includes venting the secondchamber. The injection conduit preferably has a position that isinitially fluidly incommunicated with the second chamber, and thetransfer control preferably operates the transfer mechanism in the firststage of operation and fluidly communicates the injection conduit withthe second chamber in the first stage of operation. Preferably, thetransfer control includes a cap associated with the container anddisposed to cover the injection conduit prior to the first stage ofoperation. Also, the cap is preferably separable from the injectionconduit and container after the first stage of operation. Preferably,the injector includes a cap release in locking association with the capto prevent operation thereof. The cap release is positionable in arelease position in which the cap release releases the cap to permitoperation thereof in the first stage of operation.

The injection conduit preferably includes a communicating needleportion, and the transfer control is operable to relatively move thecommunicating needle portion with respect to the second chamber topierce the container to fluidly communicate the second chamber with thecommunicating needle portion in the first stage of operation. Theinjection conduit also preferably includes an injecting needle portiondisposed and configured to pierce the skin of the patient for assistingthe injection of the fluid in the second stage.

Preferably, the energy source and firing mechanism are configured fordelivering the fluid in a jet to an injection site within the patienttissue remote from the injecting needle. The injection conduitpreferably includes a jet nozzle disposed and configured to deliver thefluid in a jet into the patient during the second stage of operation topierce the skin of the patient for assisting the injection of the fluidin the second stage.

Preferably, the second chamber comprises the medicament, and the fluidin the first chamber is a diluent configured for dissolving orsuspending the medicament therein for injection into the patient. Theenergy source is preferably associated to power the transfer mechanismto transfer the fluid to the second chamber. The preferred injector alsoincludes an injection trigger mechanism operably associated with thefiring mechanism to operate the firing mechanism in the second stage.The transfer and firing mechanisms can include a firing ram that ismovable over a first throw in the first stage of operation and a secondthrow in the second stage of operation, the energy source in biasingassociation with the ram in each stage of operation to power the ram.The injection trigger mechanism is configured to block movement of theram beyond the first throw, the injection trigger being acuatable torelease the ram to travel over the second throw.

The injector also preferably includes a retractable guard that ismovable between a protecting position in which the injection conduit isdisposed within the guard, and an injecting position in which aninjection needle portion of the injection conduit is exposed forinjection of the fluid in the patient. Preferably, the injection triggermechanism is configured for operating the firing mechanism in the secondstage after the retractable guard is retracted from the protectingposition. Also, the retractable guard can be operably associated withthe injection trigger mechanism to cause the injection trigger mechanismto operate the firing mechanism when the guard is retracted to theinjecting position.

In another preferred embodiment, the injector includes a container thatincludes a fluid chamber containing a medicament therein, the fluidchamber comprising a needle hub at the distal end thereof, and aninjection conduit configured for directing the medicament fired from thecontainer into the patient, the injection conduit having a position thatis fluidly incommunicated with the fluid chamber. The injector alsoincludes a transfer control operable to fluidly communicate theinjection conduit with the needle hub of the fluid chamber. The transfercontrol includes a cap associated with the container and disposed tocover the injection conduit, the cap being separable from the injectionconduit upon operating the transfer control to fluidly communicate theinjection conduit with the needle hub.

Preferably, the injection conduit includes a communicating needleportion, the transfer control being operable to relatively move thecommunicating needle portion with respect to the fluid chamber to piercethe container adjacent the needle hub to fluidly communicate the fluidchamber with the communicating needle portion.

A trigger device can be associated with the energy source and the firingmechanism, with the triggering device being operable in a firsttriggering stage, which causes the firing mechanism to operate in thefirst stage of operation. The triggering device can be configured suchthat only after the firing mechanism has operated in the first stage ofoperation, the triggering device is operable in a second triggeringstage which causes the firing mechanism to operate in the second stageof operation. The triggering device can have a single control that isoperable in the first and second triggering stages, or separate controlsto operate in each of the first and second triggering stages.

The present invention thus provides an injector that enablesreconstitution of a liquid medicament preparation, preferably just priorto injection, to enable easy and effective delivery of the medicament toa patient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a preferred embodiment of aninjector constructed according to the present invention, showing theinjector with a cap associated therewith;

FIG. 2 is a perspective view of the distal end of the housing thereof,with the cap removed;

FIG. 3 is a side view of a flex arm, flex arm cam, and an outer sleevearm of the injector of FIG. 1;

FIG. 4 is a perspective view of another embodiment of an injector devicewith the cap being removed; and

FIG. 5 is a perspective view thereof during injection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a preferred embodiment of an injector 10 has atubular outer housing 12 having a proximal end 6 and a distal end 8, andconfigured for allowing a user to handle the injector 10 and positionthe injector near or adjacent an injection location of a patient. Theouter housing 12 preferably houses most of the components of theinjector 10.

A cap 100 is associated with the outer housing 12 at the distal end 8and is configured for covering an injection conduit, which can be aneedle 126, or a jet nozzle, for example. The cap 100 preferablyincludes engagement portions configured for removable engagement withouter housing 12. As shown in the preferred embodiment of FIGS. 1 and 2,the cap 100 preferably includes a radially recessed neck 101 extending adistance 108 from the proximal end thereof. The neck 101 preferably hasa smaller diameter than the remaining portion of the cap 100, but canhave the same or larger diameter in other embodiments. A pair ofengagement portions 102 extend preferably proximally towards the outerhousing 12 from the neck 101, such as on opposing sides there. Each ofthe engagement portions 102 preferably extends circumferentially aroundless than about a quarter, and more preferably less than about a fifth,of the total circumference of the neck 101. The outer radial surface ofthe engagement portions 102 is preferably a threaded surface 103configured for threadably associating with a portion of the outerhousing 12. The engagement portions 102 also preferably include a notch104 at the proximal end thereof and which is configured for associatingwith another portion of the outer housing 12.

The distal end of the outer housing 12 also preferably includesengagement portions 106 configured for removable engagement with the cap100. Engagement portions 106 extend distally from positions to engagethe cap engagement portions 102, and in this embodiment are disposeddiametrically opposite sides of the distal end 8 of the outer housing12. Similar to the engagement portions 102 of the cap 100, theengagement portions 106 of the outer housing 12 preferably extendcircumferentially around less than about a quarter, and more preferablyless than about a fifth, of the total circumference of the distal end 8of the outer housing 12. The inner radial surface of the engagementportions 106 is preferably a threaded surface 107. Additionally, theengagement portions 106 preferably define a pair of gaps 105therebetween, the circumferential length of the gaps 105 preferablylarger than the circumferential length of the engagement portions 102 ofthe cap 100.

Preferably, the width between circumferentially adjacent engagementportions 106 of the outer housing 12 is greater than the width betweenengagement portions 102 of the cap 100, such that when the cap 100 andouter housing 12 are engaged with each other as shown in FIG. 1, thethreaded surface 103 of the engagement portions 102 are in threadedassociation with the threaded surface 107 of the engagement portions106, with the engagement portions 102 disposed radially inward withrespect to the engagement portions 106.

One or both of the engagement portions 106 preferably further includes acap lock mechanism 110 that is moveable between a blocking position anda release position. The cap lock mechanism 110 includes an actuationportion 111 that is operable by the user, a blocking portion 112, and apivot 113 that is mounted preferably to the outer housing 12. When theengagement portions 102 and 106 are in threaded association with eachother such that the cap 100 and the outer housing 12 are engaged, eachcap lock mechanism 110 is resiliently biased to the blocking positionsuch that each blocking portion 112 is disposed within respectivenotches 104. In this position, the blocking portion 112 preventsrotation of the cap 100 with respect to the outer housing 12, at leastin a direction that would allow cap release, and preferably in bothdirections. Movement of the cap 100 in the proximal direction withrespect to the outer housing 12 is also thus prevented. Actuation of thecap lock mechanism 110, for example, by depressing the actuation portion111 radially inward, causes the blocking portion 112 to pivot proximallyabout pivot 113 to a release position. As a result, the blocking member112 pivots out of association with the notch 104 to a position in whichrotation in a cap release direction is permitted, and no longer preventsor obstructs movement of the cap 100 in the proximal direction withrespect to the outer housing 12. Preferably, the actuation portion 111is a button, although it can be any other suitable actuation member inother embodiments, and alternative mechanisms can be used to lock thecap in a protective position. In other embodiments, the cap lockmechanism can be mounted on the cap and be disengageable with notcheslocated on the engagement portions of the outer housing.

The interior of the cap 100 preferably includes a hub-engagement portion120, which is preferably substantially annular, that defines a holdingarea 122 therein. The hub-engagement portion 120 is preferablyconfigured for reception in axial opening 74 of guard 66 of the injector10. Releasably mounted within the holding area 122 is a needle hub 124to which an injection needle 126, or other injection conduit, ismounted. In a needle-free embodiment, a jet nozzle can be mountedthereto. The needle hub 124 preferably is in a snap-lock associationwith the holding area 122 of the cap 100, but alternatively can beabutting the cap for free removal therefrom. The needle 126 preferablyincludes a piercing end 125 and an injection end 127 that terminates inan injection tip. The injection end 127 is preferably configured asknown in the art to penetrate the tissue of a patient, preferably theskin, at the injection location. A needle bore extends through theneedle 126 forming a conduit for the medicament. Preferably, the needlehub 124 is attached to the needle 126 so that the piercing end 125 isoriented proximally, and the injection end 127 is oriented distally,with respect to the outer housing 12.

In other embodiments, the cap and distal end of the housing can havedifferent configurations for allowing removable engagement therebetween.For example, the cap and housing can include associable bayonetfittings, latch fittings, snap fittings, or other suitable attachmentstructures.

The injector 10 also includes container support member 16 housed withinand mounted with the inner housing 13. The container support member 16is configured to hold and position a container within the injector 10.The container can be, for example, a cartridge 18 or any other suitablecontainer for holding medicament therein. In the preferred embodiment,the container support member 16 is substantially fixed to the innerhousing 13, such as by snaps, an adhesive, a weld, or another knownattachment, but may be mounted therein in other manners.

The cartridge 18 preferably includes a container portion 24 that definesin its interior a diluent chamber 22, which is preferably prefilled witha liquid diluent, and a medicament or drug chamber 23, which ispreferably prefilled with a particulate drug. The container portion 24is preferably tubular or cylindrical in shape. The diluent chamber 22 ispreferably aligned with and disposed proximally with respect to themedicament chamber 23. Additionally, the diluent chamber 22 is definedby a first plunger 28 at the proximal end of the chamber, a secondplunger 29 at the distal end of the chamber, and by the wall of thecontainer portion 24. Similarly, the medicament chamber 23 is defined bythe second plunger 29 at the proximal end of the chamber, a membrane,septum 30, or stopper at the distal end of the chamber, and by the wallof the container portion 24. The distal end of the medicament chamber23, adjacent the septum 30, is preferably configured for engagement andmounting of the needle hub 124 therewith.

A preferred material for the container portion 24 is glass, for example,borosilicate glass that is compatible with most medicaments, but othersuitable materials can be used in other embodiments. The first andsecond plungers or stoppers 28, 29, and the septum 30 seal therespective contents of diluent chamber 22 and medicament chamber 23therein.

The container 18 also preferably includes a by-pass or a reconstitutionbulge 32 where the walls of the container are flared radially outwardalong a longitudinal length thereof. As such, the radial diameter of thereconstitution bulge 32 is preferably substantially larger than theremaining portions of the container 18. Preferably, the radial diameterand the longitudinal length of the reconstitution bulge 32 is alsosubstantially larger than that of the second plunger 29. Thereconstitution bulge 32 is preferably located within the medicamentchamber 23 before the injection is commenced or the contents of thediluent and medicament chambers are combined.

The injector 10 also preferably includes a flex arm cam member 40, flexarms 44, and ram arms 48 contained within the outer housing 12, as shownin FIG. 1. FIG. 3 shows a side view of the relationship between suchcomponents. The flex arm cam member 40 is preferably disposed near thedistal end of the outer housing 12 such that base 41 of the flex arm cammember 40 is proximally adjacent the cap 100. The flex arm cam member 40also includes flex arm cams 42 that extend proximally from the base 41to adjacent a distal portion of one of the flex arms 44. The flex armcams 42 also define a slot 43 therebetween configured for receiving aportion of the ram arm 48.

The distal end of the of the flex arm 44 can be mounted to inner housing13 or another suitable portion of the injector 10. The distal portion ofthe flex arms 44 are disposed radially inward with respect to the flexarm cams 42. The flex arms 44 extend proximally from the flex arm cams42. The flex arms 44 are shown in a blocking position in FIG. 1. Theflex arms 44 are preferably made of a resilient, flexible material suchthat the proximal ends of the flex arms 40 can flex radially inward uponapplication of a force thereto to assume a release position.

In the blocking position, the proximal ends of each flex arm 44 isdisposed in longitudinal abutment with, and preferably in substantiallongitudinal alignment with, the distal end of a respective ram arm 48.The ram arms 48 further extend proximally therefrom to respectiveshoulders 49, which extend radially inward from each ram arm 48.Preferably, the shoulder 49 is attached to ram 60, which is associatedwith and biased by an energy source, which in the embodiment of FIG. 1is a compression spring 62, although other suitable energy sources canalternatively be used such as elastomer, compressed-gas springs, or gasgenerators. A preferred type of compression spring is a coil spring. Asa result, the ram arms 48 are also biased distally by the spring 62, andthus the distal end of each ram arm 48 is biased against the proximalend of each flex arm 44 when the flex arms are in the blocking position.The distal end of the ram 60 is disposed adjacent the proximal end ofthe first plunger 28. Although the ram 60 is biased distally against thefirst plunger 28 by the spring 62, the ram 60 is prevented fromdisplacing the first plunger 28 because the ram arms 48 are blocked bythe flex arms 44.

The ram 60 also includes a proximal portion that includes a shaft 63 andterminates proximally at enlarged portion or end 64. The enlarged end 64preferably has a radial diameter that is substantially greater than thatof the shaft 63, and which is also too large to fit through aperture 58between the trigger protrusions 56, which thus prevents or impedesdistal movement of the ram 60 past where the trigger protrusions 56would abut the enlarged end 64.

The features of the injector 10 as described above advantageously allowthe injector 10 to complete a first stage of operation, whicheffectively prepares the medicament and readies the injector 10 forinjection. Prior to commencement of the first stage of operation, theinjector 10 is preferably oriented such that the cap 100, which is inthreaded association with the outer housing 12, is above the rest of theinjector 10, as shown in FIG. 4. In some embodiments, a safety wrappingis affixed to the cap and the housing, the removal of which is requiredin order to commence the first stage of operation. Additionally, thesafety wrapping can include indicia thereon to indicate that theinjector should be oriented with the cap above the rest of the injectorprior to commencing the first stage of operation, as well as otherinstructions.

In the preferred embodiment, the first stage of operation is initiatedby actuation or depression of the cap lock mechanisms 110 to enable thecap 100 to be unlocked from fixed engagement with the outer housing 12.Upon actuation of the cap lock mechanisms 110, the blocking portions 112are pivoted proximally about the pivot 113 to the release position, andthus the cap 100 is free to rotate. Upon rotation of the threads, thecap 100 moves proximally with respect to the outer housing 112, as shownin FIG. 4. Preferably, the cap 100 is able to simultaneously rotate andmove proximally. Instead of threads, alternative embodiments can useother mechanisms, such as modified bayonet fittings of the cap to thehousing, or by a cam mechanism. The cap 100 is preferably able to moveproximally with respect to the outer housing 12 until a proximal portionof the cap 100 contacts the distal end of the engagement portions 106,which can act to limit proximal movement of the cap 100. Preferably, aquarter-turn rotation of the cap 100 is sufficient to move the cap toactuate the first stage mechanism or transfer mechanism, which in thisembodiment includes cap 100, flex arm cam member 40, flex arms 44, andram arms 48, and also to completely disengage the respective threadedsurfaces 103, 107 of the engagement portions 102, 106 from threadedassociation with each other (e.g., rotating the cap so as to dispose theengagement portions 102 within the gaps 105 defined between theengagement portions 106, or vice versa). In other embodiments, the capand housing can be configured to require rotation of the cap first untildisengagement of the engagement portions, subsequently followed bymovement of the cap proximally relative to the housing.

In another embodiment, as shown in FIG. 5 for example, engagementbetween the cap and the outer housing is directed by a modified bayonetfitting 130 disposed on the outer housing 12. The fitting 130 includes alongitudinal slot and a lateral slot, and the cap preferably includes acap protrusion configured to slide within the longitudinal and lateralslots. In this configuration, the cap protrusion is located at the endof the lateral slot when the cap and outer housing are engaged, anddisengagement is preferably achieved by rotation of the cap such thatthe cap slides along the lateral slot, followed by longitudinal movementof the cap away from the outer housing such that the cap slides alongthe longitudinal slot to separate the cap therefrom.

In the preferred embodiment, rotation of the cap 100 with respect to theouter housing 12 disengages the engagement portions 102, 106 fromthreaded association with each other, thus allowing the cap 100 to becompletely removed from association with the outer housing 12 by pullingthe cap 100 distally away therefrom. Prior to such removal of the cap,however, movement of the cap 100 proximally with respect to the outerhousing 12 also preferably initiates the first stage of operation, whichpreferably includes attaching the injection conduit in fluidcommunication with the medicament chamber 23.

For example, movement of the cap 100 in the proximal direction alsomoves the needle hub 124 proximally such that the needle hub 124 isreceived on the distal end of the medicament chamber 23 and securelymounted thereto. Preferably, the needle hub 124 has a snap-lockassociation with the distal end of the medicament chamber 23 that is ofgreater strength than the snap-lock association between the needle hub124 and the holding area 122. Thus, the needle hub 124 will remainmounted to the distal end of the medicament chamber 23 even afterremoval of the cap 100 from the injector 10 by pulling the cap distally.

Additionally, upon moving the needle hub 124 proximally for mounting,the piercing end 125 of the needle 126 preferably pierces or puncturesthe septum 30 at the distal end of the medicament chamber 23. This putsthe bore of the needle 126 in fluid communication with the medicamentchamber 23 and the medicament therein, and is open at the needle tip 127to inject the medicament therethrough. The fluid communication betweenthe needle 126 and the medicament chamber 23 also acts to vent thechamber, thus allowing air within the chamber to escape or be releasedthrough the bore of the needle 126, such as upon movement of theplungers 28, 29 through the diluent and medicament chambers 22, 23.Orientation of the injector 10 with the cap 100 above the injector 10advantageously facilitates efficient venting of the medicament chamber23, without the medicament leaking from the needle hub 124.

Movement of the cap 100 in the proximal direction also causes a proximalside 80 of cap 100 to contact and push the base 41 of the flex arm cammember 40. Upon engagement by the proximal side 80, the flex arm cammember 40 is also moved in the proximal direction, sliding the flex armcams 42 proximally along and against the distal portions of the flexarms 44. The flex arm cams 42 thus cam the flexible flex arms 44radially inwardly from the blocking position to the release positionwith respect to the ram arms 48. Because the flex arms 44 in the releaseposition are no longer longitudinally aligned with the ram arms 48, thespring 62 is able to move the ram 60 in the distal direction until theenlarged end 64 reaches aperture 58, where the trigger protrusions 56prevent further distal movement of the ram 60. In the first stageoperation, the ram 60 preferably moves longitudinally by a predeterminedfirst amount, which is less than full travel. As the ram 60 movesdistally, the ram arms 48 also slide distally radially over the flexarms 44, and the distal portions of the ram arms 48 are received withinslots 43 between the flex arm cams 42.

Movement of the ram 60 distally also moves the first plunger 28 in thedistal direction, pushing the diluent in the diluent chamber 22, whichpushes the second plunger 29 in the distal direction until secondplunger 29 reaches the reconstitution bulge 32. When the second plunger29 enters the reconstitution bulge 32, a fluid passageway is createdbetween the diluent chamber 22 and the medicament chamber 23, allowingdiluent from the diluent chamber 22 to enter and mix with the medicamentin the medicament chamber 23 as the diluent chamber 22 is reduced involume because the first plunger 28 continues to move towards the secondplunger 29. Preferably, the first stage mechanism is configured to movethe first plunger 28 until contacting second plunger 29 in the bulge 32,but lesser or greater movement can be suitable in some embodiments.

Further mixing of the diluent and medicament in the medicament chamber23 to suspend or dissolve the medicament in the diluent can beaccomplished by shaking of the injector 10. In some embodiments, forexample the embodiment shown in FIGS. 4 and 5, the outer housing 12 caninclude a transparent window portion 14 adjacent the medicament chamber23 such that the user can physically inspect the extent of mixing of thesuspension through the window.

At this point, the first stage of operation is completed and theinjector 10 is ready for injection of the mixed medicament from themedicament chamber 23. Injection is preferably achieved by completion ofa second stage of operation, which uses a second stage mechanism orfiring mechanism that includes guard 66, trigger mechanism 52, and ram60 in this embodiment. The user-operable trigger device to activate thedevice in both first and second stages of operation can include a singlecontrol that is operated in first and second triggering stages, or, asin the preferred embodiments described, can include separateuser-manipulable controls that are operated separately from each other.For example, the control to initiate the second stage can be operableonce the first stage is completed, but with the second stage mechanismkeeping the injector from firing prior to its activation.

The injector 10 includes a trigger mechanism 52 that is preferablyhoused within the proximal end of the outer housing 12. The triggermechanism 52 includes a portion of the inner portion or housing 13 thatcan be attached to the outer housing 12, such as by snaps, an adhesive,a weld, or other known attachment. Trigger protrusions 56 extendradially inwardly from the proximal end of trigger arms 57 and areresiliently biased outwardly. Trigger protrusions 56 form the aperture58 about the shaft 63 of the ram 60, the shaft 63 being received in theaperture 58. The shaft 63 is preferably at least as long as thelongitudinal movement of the ram 60 required in the first stage ofoperation. Upon movement of the ram 60 in the distal direction duringthe first stage of operation, the trigger protrusions 56 enter intoblocking association with the enlarged end 64 of the ram 60 to preventfurther distal movement of the ram 60 prior to the firing of theinjector 10 upon actuation of the trigger mechanism 52.

A trigger member of the trigger mechanism 52, such as a latch portion orhousing 61, is provided exterior to the inner housing 13 to retain thetrigger protrusions 56 in the blocking association with the enlarged end64 after the first stage of operation to prevent premature firing of theinjector 10. The latch housing 61 is slideable inside the outer housing12 with respect to the inner housing 13, preferably in an axialdirection, and the latch housing 61 preferably surrounds the innerhousing 13.

The distal end of the outer housing 12 preferably includes a needleguard 66 that is moveable with respect to the outer housing 12. Theneedle guard 66 is retractable between a protecting position and aninjecting position. In the protecting position, the needle 126 isdisposed within the guard 66. The needle guard 66 is retractable,preferably into the outer housing 12, in a proximal direction to theinjecting position, in which the injection portion 127 of the needle 126is exposed for insertion into a patient. In the preferred embodiment,the proximal movement of the guard is prevented substantially in theinjecting position. The guard 66 is preferably resiliently biaseddistally towards the protecting position by compression coil spring 72.Also, the needle guard 66 has an axial opening 74 to allow the needle126 pass there through, and which may be sized according to the type ofinjector desired. The needle guard 66 extends proximally through theinjector 10 and is of unitary with the latch housing 61.

Other embodiments can incorporate alternative trigger mechanisms foractuating firing of the injector. For example, the injector can includea button or other suitable depressible member on the outer housing that,upon depression thereof, actuates firing of the injector.

In the preferred embodiment, the second stage of operation to fire theinjector 10 is initiated by retracting the guard 66 to the injectingposition, such as by pushing the guard against the patient's skin. Theneedle guard 66 is associated with the latch housing 61 such that whenthe guard 66 is displaced proximally, it slides the latch housing 61also in a proximal direction to release the trigger protrusions 56 fromblocking association with the enlarged end 64 of the ram 60. Preferably,the latch housing 61 has a latching portion that abuts the inner housing13 in an association to bias and maintain the trigger protrusions 56positioned in the blocking association with the enlarged end 64 prior tothe firing of the injector 10. When the latch housing 61 is slidproximally by the retracting of the guard 66 to the injecting position,the latching portion slides beyond the portion of inner housing 13 thatit contacts to flex the trigger protrusions 56, allowing the triggerprotrusions 56 to move radially outwardly with respect to the shaft 63and therefore from the blocking association with the enlarged end 64.When this happens, i.e., when the trigger mechanism 52 is actuated, thespring 62 biases the ram 60 against the first plunger 28 to fire theinjector 10. The cartridge 18 is configured such that when the firstplunger 28 is displaced in a distal direction, the volume of themedicament chamber 23 is decreased, forcing the mixed medicament outtherefrom and through the bore of needle 24. Latch housing 61 preferablydefines trigger openings adjacent to the latching portions, which areconfigured to receive a portion of the inner housing 13, such as thesurface disposed radially outwardly from the trigger protrusions 56. Asame energy source, such as spring 62, can be configured to power bothfirst and second stages.

In the preferred embodiment, the user can push the distal end of theinjector 10 against the patient's skin as shown in FIG. 5, pushing theneedle 126 into the skin at the injection location, preferablysubstantially at the same speed as the injector is pushed, althoughalternative embodiments can move the cartridge forward to insert theneedle. Once the needle 126 is fully inserted to an insertion point at apenetration depth in the patient's skin, the trigger mechanism 52 firesthe injection of medicament into an injection location.

Preferably, the injecting position of the guard 66 is such that apredetermined length of the end of needle 126 is exposed from the guard66. In some embodiments, such as where the opening 74 is of asufficiently large diameter, the skin of the patient maybe allowed toextend into the opening 74 when the device 10 is pressed there against,and a needle that does not protrude beyond the distal end of the guard66 can be used. In most embodiments, the distance by which the needletip extends past the distal end of the guard will be fairly close to thedepth of the insertion of the needle. Additionally, in some embodiments,the distal surface of the guard can be discontinuous.

The injector 10 can be configured for various types of subcutaneousinjections, intradermal injections, intravascular injections, or othertypes of injections. In the preferred embodiment, the guard 66 isconfigured to allow insertion of the needle to a penetration depth inthe skin that is up to about 5 mm below the skin surface. Morepreferably, the penetration depth is less than about 4 mm, and in oneembodiment is less than about 3 mm. Preferably, the insertion depth isat least about 0.5 mm and more preferably at least about 1 mm. Inanother embodiment, the distance by which the needle extends past theguard 66 or the distal surface of the guard 66 that contacts the skin isup to about 5 mm, more preferably up to about 4 mm, and in oneembodiment up to about 3 mm. Preferably, extension distance is at leastabout 0.5 mm, more preferably at least about 1 mm, and most preferablyat least about 2 mm. In a preferred embodiment, tip 127 of the needle126 extends by a distance of around 2.5 mm beyond the portion of theguard 66 that contacts the skin in the injecting position. Inalternative embodiments, the needle tip stops behind or proximal to theguard, and penetrates the skin that is pushed into the guard.

In another embodiment, such as for intramuscular injection, the injectoris configured to allow the needle to be inserted into the patient to apenetration depth in the skin, or alternatively beyond the distalsurface of the guard, by a distance of up to about 15 mm. In oneembodiment, this distance is about between 10 mm and 14 mm. In anembodiment for jet injection of epinephrine for instance, a preferredpenetration depth or distance beyond the guard is between about 12 mmand 13.5 mm, and most preferably around 12.7 mm. Jet injection with thislength needle improves the distribution of the medicament in the patienttissue compared to non-jet injection. Other exposed needle lengths canbe selected for jet injection to different depths below the skin, with apreferred overall penetration length of between about 0.5 mm and about20 mm. In these embodiments, the needle guard is preferably configuredfor retracting from a protecting position, preferably covering theentire needle, to an injecting position, in which the desired length ofthe end of the needle is exposed.

In some embodiments, the energy source, which is preferably spring 62,and the container, which is preferably cartridge 18, are configured tojet inject the medicament into the patient to an injection site. Thespring 62 applies a force on the ram 60 to bias the first plunger 28that is preferably sufficient to elevate the pressure within the diluentand medicament chambers 22, 23 to a level high enough to eject themedicament from the needle 126 as a jet. Jet injection is to beunderstood as an injection with sufficient velocity and force to drivethe medicament to locations remote from the needle tip 127. The jetinjector embodiments deliver a jet injection, the medicament is jetinjected distally or in other directions, such as generally radially bythe elevated pressure jet, which beneficially improves the distributionof the medicament after the injection and keeps a large bolus fromforming that can detrimentally force the medicament to leak back out ofthe patient around the needle or through the hole left behind by theneedle after it is removed. In alternative autoinjector embodiments thatuse needles, the injection pressures are relatively very low, and themedicament exits the needle tip inside the patient and is typicallydeposited locally around the needle in a bolus.

Preferably, the needle 127 is between 26 and 28 gage, and are mostpreferably around 27 gage, but alternatively other needle gages can beused where the other components are cooperatively configured to producethe desired injection. Preferably, the components of the injector 10 areconfigured to jet inject the medicament to a subterraneous injectionsite.

Preferred injection rates are below about 0.75 mL/sec., more preferablybelow about 0.6 mL/sec., and preferably at least about 0.2 mL/sec., morepreferably at least about 0.3 mL/sec, and most preferably at least about0.4 mL/sec. Preferably, the injection of the entire amount of medicamentis completed in less than about 4 seconds, more preferably in less thanabout 3 seconds, and most preferably in less than about 2.5 seconds.Preferably, the medicament injection takes at least about 1 second, andmore preferably at least 1.5 seconds, and most preferably at least about1.75 seconds. A preferred embodiment injects the medicament at about 0.5mL/sec., completing the injection of 1 mL in about 2 seconds.

The entire amount of mixed medicament contained and injected from thecontainer 18 is preferably between about 0.02 mL and 4 mL, andpreferably less than about 3 mL, and in the preferred embodiment isaround 1 mL. Larger volumes may also be selected depending on theparticular medicament and dosage required. Preferably, the cartridge 18shown in FIG. 1 is assembled into the remaining parts of the injector 10already containing the desired amount of diluent and medicament therein.In a preferred embodiment, the container 18 contains about 1 mL ofdiluent and medicament.

While illustrative embodiments of the invention are disclosed herein, itwill be appreciated that numerous modifications and other embodimentsmay be devised by those skilled in the art. For example, the featuresfor the various embodiments can be used in other embodiments. Therefore,it will be understood that the appended claims are intended to cover allsuch modifications and embodiments that come within the spirit and scopeof the present invention.

What is claimed is:
 1. An injector for injecting a medicament into apatient, comprising: a container defining: a first chamber containing afluid, and a second chamber; an injection conduit configured fordirecting the fluid fired from the container into the patient; atransfer mechanism operable by a user to transfer the fluid from thefirst chamber to the second chamber in a first stage of operation; afiring mechanism operable by the user for firing the fluid from thesecond chamber through the injection conduit in a second stage ofoperation; and an energy source in powering association with thetransfer and firing mechanisms to drive transfer and firing mechanismsin both the first and second stages.
 2. The injector of claim 1, furthercomprising an injection trigger mechanism operably associated with thefiring mechanism to operate the firing mechanism in the second stage. 3.The injector of claim 2, wherein the transfer and firing mechanismscomprise a firing ram that is movable over a first throw in the firststage of operation and a second throw in the second stage of operation,the energy source in biasing association with the ram in each stage ofoperation to power the ram.
 4. The injector of claim 3, wherein theinjection trigger mechanism is configured to block movement of the rambeyond the first throw, the injection trigger being actuatable torelease the ram to travel over the second throw.
 5. The injector ofclaim 1, further comprising a retractable guard that is movable between:a protecting position in which the injection conduit is disposed withinthe guard; and an injecting position in which an injection needleportion of the injection conduit is exposed for injection of the fluidin the patient; wherein the injection trigger mechanism is configuredfor operating the firing mechanism in the second stage after theretractable guard is retracted from the protecting position.
 6. Theinjector of claim 5, wherein the retractable guard is operablyassociated with the injection trigger mechanism to cause the injectiontrigger mechanism to operate the firing mechanism when the guard isretracted to the injecting position.
 7. The injector of claim 1, furthercomprising a transfer control that is manually operable to operate theinjector in the first stage of operation, which further comprisesventing the second chamber.
 8. The injector of claim 1, wherein theinjection conduit has a position that is fluidly incommunicated with thesecond chamber, the injector further comprising a transfer control thatis manually operable to operate the transfer mechanism in the firststage of operation and to fluidly communicate the injection conduit withthe second chamber in the first stage of operation.
 9. The injector ofclaim 8, wherein the transfer control comprises a cap associated withthe container and disposed to cover the injection conduit prior to thefirst stage of operation, which cap is separable from the injectionconduit and container after the first stage of operation.
 10. Theinjector of claim 8, wherein the injection conduit comprises acommunicating needle portion, the transfer control operable torelatively move the communicating needle portion with respect to thesecond chamber to pierce the container to fluidly communicate the secondchamber with the communicating needle portion in the first stage ofoperation.
 11. The injector of claim 10, wherein the injection conduitcomprises an injecting needle portion disposed and configured to piercethe skin of the patient for assisting the injection of the fluid in thesecond stage.
 12. The injector of claim 11, wherein the energy sourceand firing mechanism are configured for delivering the fluid by jetinjection to an injection site within the patient tissue remote from theinjecting needle.
 13. The injector of claim 10, wherein the injectionconduit comprises a jet nozzle disposed and configured to deliver thefluid by jet injection into the patient during the second stage ofoperation to pierce the skin of the patient for assisting the injectionof the fluid in the second stage.
 14. The injector of claim 10, whereinthe transfer control comprises a cap associated with the container anddisposed to cover the injection conduit prior to the first stage ofoperation, which cap is separable from the injection conduit andcontainer after the first stage of operation.
 15. The injector of claim14, further comprising a cap release in locking association with the capto prevent operation thereof, and being positionable in a releaseposition in which the cap release releases the cap to permit operationthereof in the first stage of operation.
 16. The injector of claim 1,wherein the second chamber comprises a medicament, and the fluidcomprises a diluent configured for dissolving or suspending themedicament therein for injection into the patient.
 17. An injector forinjecting a medicament into a patient, comprising: a container defining:a first chamber containing a fluid, and a second chamber; a firingmechanism configured for transferring the fluid from the first chamberto the second chamber in a first stage of operation, and for firing thefluid from the second chamber in a second stage of operation; aninjection conduit configured for directing the fluid fired from thecontainer into the patient; an energy source in powering associationwith the firing mechanism to drive firing mechanism in the first andsecond stages; a trigger device associated with the energy source andthe firing mechanism and being operable in a first triggering stagewhich causes the firing mechanism to operate in the first stage ofoperation, wherein the triggering device is configured such that afterthe firing mechanism has operated in the first stage of operation, thetriggering device is operable in a second triggering stage which causesthe firing mechanism to operate in the second stage of operation.
 18. Aninjector for injecting medicament into a patient, comprising: acontainer comprising a fluid chamber containing a medicament therein,the fluid chamber comprising a needle hub at the distal end thereof; aninjection conduit configured for directing the medicament fired from thecontainer into the patient, the injection conduit having a position thatis fluidly incommunicated with the fluid chamber; a firing mechanismoperable by the user for firing the medicament from the fluid chamberthrough the injection conduit; an energy source in powering associationwith the firing mechanism to drive firing mechanism; and a transfercontrol operable to fluidly communicate the injection conduit with theneedle hub of the fluid chamber, the transfer control comprising a capassociated with the container and disposed to cover the injectionconduit; wherein the cap is separable from the injection conduit uponoperating the transfer control to fluidly communicate the injectionconduit with the needle hub.
 19. The injector of claim 20, wherein theinjection conduit comprises a communicating needle portion, the transfercontrol being operable to relatively move the communicating needleportion with respect to the fluid chamber to pierce the containeradjacent the needle hub to fluidly communicate the fluid chamber withthe communicating needle portion.